1. Technical Field
The present invention relates to a vibratory gyroscope and a vibrator capable of being preferably used in this vibratory gyroscope.
2. Related Arts
Japanese laid-open publication Tokkaihei No. 7-83671 has disclosed a vibratory gyroscope using a tuning-fork vibrator made by joining a total of three vibration pieces composed of a middle driving vibration piece and two detecting vibration pieces, being at both sides of the middle driving vibration piece all joined to a base part in one body. FIG. 1 shows the composition of an example of such a vibratory gyroscope. In the example shown in FIG. 1, a tuning-fork vibrator 71 forming a vibratory gyroscope is composed of three vibration pieces which are composed of a middle driving vibration piece 73 and two detecting vibration pieces 72 and 74 arranged at both sides of it nearly in parallel with it, and a base part 75 with which the driving vibration piece 73 and the detecting vibration pieces 72 and 74 are joined in one body.
In the above-mentioned tuning-fork vibrator 71, the driving vibration piece 73 is vibrated in the X-Z plane by an unillustrated driving means provided on the driving vibration piece 73. And the left and right detecting vibration pieces 72 and 74 are resonated in the same X-Z plane. When a turning angular rate (.omega.) acts around the axis of symmetry Z of the tuning-fork vibrator 71, a Coriolis force (f) acts on each of the detecting vibration pieces 72 and 74. Since the detecting vibration pieces 72 and 74 are vibrating in the X-Z plane, vibration in the Y-Z plane is induced in the detecting vibration pieces 72 and 74. A turning angular rate is measured by detecting this vibration by means of an unillustrated detecting means provided on each of the detecting vibration pieces 72 and 74.
In a former vibratory gyroscope of the above-mentioned composition, in case of forming the vibratory gyroscope by supporting the tuning-fork vibrator 71, the vibrator 71 is supported by fixing the entire end part 76 of the base part 75 of the tuning-fork vibrator 71 opposite to the other end part at which the driving vibration piece 73 and the detecting vibration pieces 72 and 74 exist, or by fixing an unillustrated supporting vibration piece at a position of this end part 76 corresponding to the axis of symmetry Z. Therefore, it cannot be said that a Coriolis force generated by a turning angular rate is efficiently utilized for action of a detecting vibration in the detecting vibration pieces 72 and 74, and there is a problem that the sharpness of resonance (Q value) of the detecting vibration in the Y-Z plane in the detecting vibration pieces 72 and 74 is low and the measurement sensitivity for a turning angular rate is low.